The invention relates generally to the area of flash photography, and more specifically to filtering xe2x80x9cred-eyexe2x80x9d from a digital camera image.
xe2x80x9cRed-eyexe2x80x9d is a phenomenon in flash photography where a flash is reflected within a subject""s eye and appears in a photograph as a red dot where the black pupil of the subject""s eye would normally appear. The unnatural glowing red of an eye is due to internal reflections from the vascular membrane behind the retina, which is rich in blood vessels. This objectionable phenomenon is well understood to be caused in part by a small angle between the flash of the camera and the lens of the camera. This angle has decreased with the miniaturization of cameras with integral flash capabilities. Additional contributors include the relative closeness of the subject to the camera and ambient light levels.
The red-eye phenomenon can be minimized by causing the iris to reduce the opening of the pupil. This is typically done with a xe2x80x9cpre-flashxe2x80x9d, a flash or illumination of light shortly before a flash photograph is taken. This causes the iris to close. Unfortunately, the pre-flash is an objectionable 0.2 to 0.6 seconds prior to the flash photograph. This delay is readily discernible and easily within the reaction time of a human subject. Consequently the subject may believe the pre-flash is the actual photograph and be in a less than desirable position at the time of the actual photograph. Alternately, the subject must be informed of the pre-flash, typically loosing any spontaneity of the subject captured in the photograph.
Those familiar with the art have developed complex analysis processes operating within a camera prior to invoking a pre-flash. Various conditions are monitored prior to the photograph before the pre-flash is generated, the conditions include the ambient light level and the distance of the subject from the camera. Such a system is described in U.S. Pat. No. 5,070,355 to Inoue et al. Although that invention minimizes the occurrences where a pre-flash is used, it does not eliminate the need for a pre-flash. What is needed is a method of eliminating the red-eye phenomenon with a miniature camera having an integral without the distraction of a pre-flash.
Digital cameras are becoming more popular and smaller in size. Digital cameras have several advantages over film cameras. Digital cameras eliminate the need for film as the image is digitally captured and stored in a memory array for display on a display screen on the camera itself. This allows photographs to be viewed and enjoyed virtually instantaneously as opposed to waiting for film processing. Furthermore, the digitally captured image may be downloaded to another display device such as a personal computer or color printer for further enhanced viewing. Digital cameras include microprocessors for image processing and compression and camera systems control. Nevertheless, without a pre-flash, both digital and film cameras can capture the red-eye phenomenon as the flash reflects within a subject""s eye. Thus, what is needed is a method of eliminating red-eye phenomenon within a miniature digital camera having a flash without the distraction of a pre-flash.